Magnetic wallpaper Dirac fermions and topological magnetic Dirac insulators

• Published in: npj computational materials Vol. 9; no. 1; pp. 65 - 8
• Main Authors: Hwang, Yoonseok, Qian, Yuting, Kang, Junha, Lee, Jehyun, Ryu, Dongchoon, Choi, Hong Chul, Yang, Bohm-Jung
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25-04-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/2792/4128; 639/766/119/997; Characterization and Evaluation of Materials; Chemistry and Materials Science; Computational Intelligence; Crystals; Eigenvalues; Fermions; First principles; Insulators; Materials Science; Materials selection; Mathematical and Computational Engineering; Mathematical and Computational Physics; Mathematical Modeling and Industrial Mathematics; Mirrors; Surface properties; Symmetry; Theoretical; Topology; Wallcoverings; Wallpaper
• ISSN: 2057-3960; 2057-3960
• DOI: 10.1038/s41524-023-01018-3

Topological crystalline insulators (TCIs) can host anomalous surface states which inherits the characteristics of crystalline symmetry that protects the bulk topology. Especially, the diversity of magnetic crystalline symmetries indicates the potential for novel magnetic TCIs with distinct surface characteristics. Here, we propose a topological magnetic Dirac insulator (TMDI), whose two-dimensional surface hosts fourfold-degenerate Dirac fermions protected by either the
p
c
′
4
m
m
or
p
4
′
g
′
m
magnetic wallpaper group. The bulk topology of TMDIs is protected by diagonal mirror symmetries, which give chiral dispersion of surface Dirac fermions and mirror-protected hinge modes. We propose candidate materials for TMDIs including Nd
4
Te
8
Cl
4
O
20
and DyB
4
based on first-principles calculations, and construct a general scheme for searching TMDIs using the space group of paramagnetic parent states. Our theoretical discovery of TMDIs will facilitate future research on magnetic TCIs and illustrate a distinct way to achieve anomalous surface states in magnetic crystals.